The present invention is related to an environmental control system. More particularly, the present invention is related to a diagnostic system for testing dampers or controllers utilized in an environment control network.
Environment control networks or facility management systems are employed in office buildings, manufacturing facilities, and the like, for controlling the internal environment of the facility. The environment control network may be employed to control temperature, airflow, humidity, lighting, or security in the internal environment.
In environment control networks, variable air volume (VAV) boxes are located throughout the facility and provide environmentally controlled air to the internal environment. The controlled air is preferably provided at a particular temperature or humidity so that a comfortable internal environment is established. The air flow of the controlled air is preferably measured in cubic feet per minute (CFM).
The VAV boxes are generally coupled to an air source which supplies the controlled air to the VAV box via duct work. The controlled air is preferably provided through a damper in the VAV box. The damper regulates the amount of the controlled air provided by the VAV box to the internal environment. The damper is generally coupled to an actuator which preferably positions the damper so that appropriate air flow is provided to the internal environment.
A controller is generally associated with each VAV box. The controller receives information related to the air flow and temperature in the internal environment and appropriately positions the actuator so that the VAV box provides the appropriate air flow to the internal environment. The controller may include sophisticated feedback mechanisms such as proportional integrated control (PI control) algorithms. Sophisticated feedback allows the actuator to be positioned more precisely.
The controller may be coupled to a communication bus within the environment control network and is able to communicate with other components within the environment control network. For example, the controller may include circuitry which indicates when the controller has experienced a catastrophic malfunction. A message indicative of this malfunction may be communicated to components within the network across the communication bus. Also, the controllers may receive hazardous warning messages on the communication bus, such as a fire warning. The controller may be configured to close all dampers in response to a fire warning. Thus, the controllers are generally capable of receiving information and messages about other components within the environment control network.
Large buildings typically have hundreds of VAV boxes which are positioned in hard to reach and visually obstructed places. For example, VAV boxes and their associated controllers are often positioned in temporary or plastered ceilings. Components associated with the VAV boxes such as actuators, dampers, sensors and controllers must be repaired when they malfunction. Malfunctioning components associated with VAV boxes may cause the internal environment or portions thereof to become too hot, too cold, too drafty, or too noisy. Heretofore, service people in charge of repairing components associated with the VAV boxes receive complaints of a most general nature about the internal environment and are required to find the VAV boxes which are responsible for the complaints. Finding these boxes among the hundreds of hidden VAV boxes is extremely difficult.
Once found, the service people must uncover the VAV boxes and manually perform diagnostics for the VAV boxes and the associated controllers by manipulating controls on the VAV boxes and controllers. Generally, service people are required to perform a visual inspection to search for mechanical failures. These service people also perform functional tests by coupling the controller to a personal computer and causing the controller to move the damper. The service people visually confirm that the damper is moving properly.
Thus, conventional environment control networks require that service people perform "hands on" diagnostic analysis on individual VAV boxes. "Hands on" diagnostic analysis imposes a relatively severe workload burden on service people because of the increased time required for the service people to find and individually test VAV boxes and associated controllers before discovering the problematic unit. Thus, there is a need for a diagnostic system or tool which is able to test controllers and VAV boxes from a remote location. Further, there is a need for a diagnostic tool which is able to test several controllers and VAV boxes simultaneously.